In the strongest public warning to date from an American official, the director of the CIA, John Brennan, today said if the Iraqi Security Forces and Shiite militias are involved in war crimes and tactics similar to ISIS, it “needs to be exposed, needs to be stopped.”

Brennan made the comments Friday in New York when asked about an ABC News report which revealed dozens of videos and photos of what appear to be men in uniforms of Iraqi Security Forces units carrying out or celebrating torture and murder against unarmed civilians, including beheadings.

“It’s tough sorting out good guys and bad guys in a lot of these areas,” said Brennan referring to scenes of “horrific human rights abuses.”

“When we see it, we do bring it to the attention of authorities and we will not work with entities that are engaged in such activities,” the CIA director said.

Earlier, Pentagon officials revealed that the Chairman of the Joint Chiefs of Staff, Army Gen. Martin Dempsey, had repeatedly warned Iraqi officials about the “conduct” of their soldiers and the militias that are fighting alongside them against ISIS.

Officials said "certain Iraqi units" have already been denied U.S. military assistance -- including weapons, equipment and training -- because of "credible information in the past" of gross human rights violations.

The Iraqi army has promised a full investigation of the photographic evidence ABC News found had been posted on social media sites connected to elite Iraqi Security Forces units and Shiite militias.